spandsp  0.0.6
t4_rx.h
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1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * t4_rx.h - definitions for T.4 FAX receive processing
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2003 Steve Underwood
9  *
10  * All rights reserved.
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU Lesser General Public License version 2.1,
14  * as published by the Free Software Foundation.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU Lesser General Public License for more details.
20  *
21  * You should have received a copy of the GNU Lesser General Public
22  * License along with this program; if not, write to the Free Software
23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24  */
25 
26 /*! \file */
27 
28 #if !defined(_SPANDSP_T4_RX_H_)
29 #define _SPANDSP_T4_RX_H_
30 
31 /*! \page t4_page T.4 image compression and decompression
32 
33 \section t4_page_sec_1 What does it do?
34 The T.4 image compression and decompression routines implement the 1D and 2D
35 encoding methods defined in ITU specification T.4. They also implement the pure
36 2D encoding method defined in T.6. These are image compression algorithms used
37 for FAX transmission.
38 
39 \section t4_page_sec_1 How does it work?
40 */
41 
42 /*! This function is a callback from the image decoders, to write the decoded bi-level image,
43  row by row. It is called for each row, with len set to the number of bytes per row. At the
44  end of the image it is called with len set to zero, to indicate the end of image condition.
45  \return 0 for OK, or non-zero for a problem that requires the image be interrupted. */
46 typedef int (*t4_row_write_handler_t)(void *user_data, const uint8_t buf[], size_t len);
47 
48 /*! Supported compression modes. */
49 typedef enum
50 {
51  /*! No compression */
53  /*! T.1 1D compression */
55  /*! T.4 2D compression */
57  /*! T.6 2D compression */
59  /*! T.85 monochrome JBIG coding with L0 fixed. */
61  /*! T.85 monochrome JBIG coding with L0 variable. */
63  /*! T.43 colour JBIG coding */
65  /*! T.45 run length colour compression */
67  /*! T.42 + T.81 + T.30 Annex E colour JPEG coding */
69  /*! T.42 + T.81 + T.30 Annex K colour sYCC-JPEG coding */
72 
73 /*! Image type */
74 typedef enum
75 {
76  T4_IMAGE_TYPE_BILEVEL = 0,
77  T4_IMAGE_TYPE_GRAY_8BIT = 1,
78  T4_IMAGE_TYPE_GRAY_12BIT = 2,
79  T4_IMAGE_TYPE_COLOUR_8BIT = 3,
80  T4_IMAGE_TYPE_COLOUR_12BIT = 4
82 
83 /*! Supported X resolutions, in pixels per metre. */
84 typedef enum
85 {
86  T4_X_RESOLUTION_R4 = 4016,
87  T4_X_RESOLUTION_R8 = 8031,
88  T4_X_RESOLUTION_300 = 11811,
89  T4_X_RESOLUTION_R16 = 16063,
90  T4_X_RESOLUTION_600 = 23622,
91  T4_X_RESOLUTION_800 = 31496,
92  T4_X_RESOLUTION_1200 = 47244
94 
95 /*! Supported Y resolutions, in pixels per metre. */
96 typedef enum
97 {
98  T4_Y_RESOLUTION_STANDARD = 3850,
99  T4_Y_RESOLUTION_FINE = 7700,
100  T4_Y_RESOLUTION_300 = 11811,
101  T4_Y_RESOLUTION_SUPERFINE = 15400, /* 400 is 15748 */
102  T4_Y_RESOLUTION_600 = 23622,
103  T4_Y_RESOLUTION_800 = 31496,
104  T4_Y_RESOLUTION_1200 = 47244
106 
107 /*!
108  Exact widths in PELs for the difference resolutions, and page widths.
109  Note:
110  The A4 widths also apply to North American letter and legal.
111  The R4 resolution widths are not supported in recent versions of T.30
112  Only images of exactly these widths are acceptable for FAX transmisson.
113 
114  R4 864 pels/215mm for ISO A4, North American Letter and Legal
115  R4 1024 pels/255mm for ISO B4
116  R4 1216 pels/303mm for ISO A3
117  R8 1728 pels/215mm for ISO A4, North American Letter and Legal
118  R8 2048 pels/255mm for ISO B4
119  R8 2432 pels/303mm for ISO A3
120  R16 3456 pels/215mm for ISO A4, North American Letter and Legal
121  R16 4096 pels/255mm for ISO B4
122  R16 4864 pels/303mm for ISO A3
123 */
124 typedef enum
125 {
126  T4_WIDTH_R4_A4 = 864,
127  T4_WIDTH_R4_B4 = 1024,
128  T4_WIDTH_R4_A3 = 1216,
129  T4_WIDTH_R8_A4 = 1728,
130  T4_WIDTH_R8_B4 = 2048,
131  T4_WIDTH_R8_A3 = 2432,
132  T4_WIDTH_300_A4 = 2592,
133  T4_WIDTH_300_B4 = 3072,
134  T4_WIDTH_300_A3 = 3648,
135  T4_WIDTH_R16_A4 = 3456,
136  T4_WIDTH_R16_B4 = 4096,
137  T4_WIDTH_R16_A3 = 4864,
138  T4_WIDTH_600_A4 = 5184,
139  T4_WIDTH_600_B4 = 6144,
140  T4_WIDTH_600_A3 = 7296,
141  T4_WIDTH_1200_A4 = 10368,
142  T4_WIDTH_1200_B4 = 12288,
143  T4_WIDTH_1200_A3 = 14592
145 
146 /*!
147  Length of the various supported paper sizes, in pixels at the various Y resolutions.
148  Paper sizes are
149  A4 (215mm x 297mm)
150  B4 (255mm x 364mm)
151  A3 (303mm x 418.56mm)
152  North American Letter (215.9mm x 279.4mm)
153  North American Legal (215.9mm x 355.6mm)
154  Unlimited
155 
156  T.4 does not accurately define the maximum number of scan lines in a page. A wide
157  variety of maximum row counts are used in the real world. It is important not to
158  set our sending limit too high, or a receiving machine might split pages. It is
159  important not to set it too low, or we might clip pages.
160 
161  Values seen for standard resolution A4 pages include 1037, 1045, 1109, 1126 and 1143.
162  1109 seems the most-popular. At fine res 2150, 2196, 2200, 2237, 2252-2262, 2264,
163  2286, and 2394 are used. 2255 seems the most popular. We try to use balanced choices
164  here.
165 */
166 typedef enum
167 {
168  /* A4 is 297mm long */
169  T4_LENGTH_STANDARD_A4 = 1143,
170  T4_LENGTH_FINE_A4 = 2286,
171  T4_LENGTH_300_A4 = 4665,
172  T4_LENGTH_SUPERFINE_A4 = 4573,
173  T4_LENGTH_600_A4 = 6998,
174  T4_LENGTH_800_A4 = 9330,
175  T4_LENGTH_1200_A4 = 13996,
176  /* B4 is 364mm long */
177  T4_LENGTH_STANDARD_B4 = 1401,
178  T4_LENGTH_FINE_B4 = 2802,
179  T4_LENGTH_300_B4 = 0,
180  T4_LENGTH_SUPERFINE_B4 = 5605,
181  T4_LENGTH_600_B4 = 0,
182  T4_LENGTH_800_B4 = 0,
183  T4_LENGTH_1200_B4 = 0,
184  /* North American letter is 279.4mm long */
185  T4_LENGTH_STANDARD_US_LETTER = 1075,
186  T4_LENGTH_FINE_US_LETTER = 2151,
187  T4_LENGTH_300_US_LETTER = 0,
188  T4_LENGTH_SUPERFINE_US_LETTER = 4302,
189  T4_LENGTH_600_US_LETTER = 0,
190  T4_LENGTH_800_US_LETTER = 0,
191  T4_LENGTH_1200_US_LETTER = 0,
192  /* North American legal is 355.6mm long */
193  T4_LENGTH_STANDARD_US_LEGAL = 1369,
194  T4_LENGTH_FINE_US_LEGAL = 2738,
195  T4_LENGTH_300_US_LEGAL = 0,
196  T4_LENGTH_SUPERFINE_US_LEGAL = 5476,
197  T4_LENGTH_600_US_LEGAL = 0,
198  T4_LENGTH_800_US_LEGAL = 0,
199  T4_LENGTH_1200_US_LEGAL = 0
201 
202 /*!
203  T.4 FAX compression/decompression descriptor. This defines the working state
204  for a single instance of a T.4 FAX compression or decompression channel.
205 */
206 typedef struct t4_state_s t4_state_t;
207 typedef struct t4_state_s t4_rx_state_t;
208 
209 /*!
210  T.4 FAX compression/decompression statistics.
211 */
212 typedef struct
213 {
214  /*! \brief The number of pages transferred so far. */
216  /*! \brief The number of pages in the file (<0 if unknown). */
218  /*! \brief The number of horizontal pixels in the most recent page. */
219  int width;
220  /*! \brief The number of vertical pixels in the most recent page. */
221  int length;
222  /*! \brief The number of bad pixel rows in the most recent page. */
223  int bad_rows;
224  /*! \brief The largest number of bad pixel rows in a block in the most recent page. */
226  /*! \brief The horizontal resolution of the page in pixels per metre */
228  /*! \brief The vertical resolution of the page in pixels per metre */
230  /*! \brief The type of compression used between the FAX machines */
231  int encoding;
232  /*! \brief The size of the image on the line, in bytes */
234 } t4_stats_t;
235 
236 #if defined(__cplusplus)
237 extern "C" {
238 #endif
239 
240 /*! \brief Prepare to receive the next page of the current document.
241  \param s The T.4 context.
242  \return zero for success, -1 for failure. */
243 SPAN_DECLARE(int) t4_rx_start_page(t4_rx_state_t *s);
244 
245 /*! \brief Put a bit of the current document page.
246  \param s The T.4 context.
247  \param bit The data bit.
248  \return TRUE when the bit ends the document page, otherwise FALSE. */
249 SPAN_DECLARE(int) t4_rx_put_bit(t4_rx_state_t *s, int bit);
250 
251 /*! \brief Put a byte of the current document page.
252  \param s The T.4 context.
253  \param byte The data byte.
254  \return TRUE when the byte ends the document page, otherwise FALSE. */
255 SPAN_DECLARE(int) t4_rx_put_byte(t4_rx_state_t *s, uint8_t byte);
256 
257 /*! \brief Put a byte of the current document page.
258  \param s The T.4 context.
259  \param buf The buffer containing the chunk.
260  \param len The length of the chunk.
261  \return TRUE when the byte ends the document page, otherwise FALSE. */
262 SPAN_DECLARE(int) t4_rx_put_chunk(t4_rx_state_t *s, const uint8_t buf[], int len);
263 
264 /*! \brief Complete the reception of a page.
265  \param s The T.4 receive context.
266  \return 0 for success, otherwise -1. */
267 SPAN_DECLARE(int) t4_rx_end_page(t4_rx_state_t *s);
268 
269 /*! \brief Set the row write handler for a T.4 receive context.
270  \param s The T.4 receive context.
271  \param handler A pointer to the handler routine.
272  \param user_data An opaque pointer passed to the handler routine.
273  \return 0 for success, otherwise -1. */
274 SPAN_DECLARE(int) t4_rx_set_row_write_handler(t4_rx_state_t *s, t4_row_write_handler_t handler, void *user_data);
275 
276 /*! \brief Set the encoding for the received data.
277  \param s The T.4 context.
278  \param encoding The encoding. */
279 SPAN_DECLARE(void) t4_rx_set_rx_encoding(t4_rx_state_t *s, int encoding);
280 
281 /*! \brief Set the expected width of the received image, in pixel columns.
282  \param s The T.4 context.
283  \param width The number of pixels across the image. */
284 SPAN_DECLARE(void) t4_rx_set_image_width(t4_rx_state_t *s, int width);
285 
286 /*! \brief Set the row-to-row (y) resolution to expect for a received image.
287  \param s The T.4 context.
288  \param resolution The resolution, in pixels per metre. */
289 SPAN_DECLARE(void) t4_rx_set_y_resolution(t4_rx_state_t *s, int resolution);
290 
291 /*! \brief Set the column-to-column (x) resolution to expect for a received image.
292  \param s The T.4 context.
293  \param resolution The resolution, in pixels per metre. */
294 SPAN_DECLARE(void) t4_rx_set_x_resolution(t4_rx_state_t *s, int resolution);
295 
296 /*! \brief Set the DCS information of the fax, for inclusion in the file.
297  \param s The T.4 context.
298  \param dcs The DCS information, formatted as an ASCII string. */
299 SPAN_DECLARE(void) t4_rx_set_dcs(t4_rx_state_t *s, const char *dcs);
300 
301 /*! \brief Set the sub-address of the fax, for inclusion in the file.
302  \param s The T.4 context.
303  \param sub_address The sub-address string. */
304 SPAN_DECLARE(void) t4_rx_set_sub_address(t4_rx_state_t *s, const char *sub_address);
305 
306 /*! \brief Set the identity of the remote machine, for inclusion in the file.
307  \param s The T.4 context.
308  \param ident The identity string. */
309 SPAN_DECLARE(void) t4_rx_set_far_ident(t4_rx_state_t *s, const char *ident);
310 
311 /*! \brief Set the vendor of the remote machine, for inclusion in the file.
312  \param s The T.4 context.
313  \param vendor The vendor string, or NULL. */
314 SPAN_DECLARE(void) t4_rx_set_vendor(t4_rx_state_t *s, const char *vendor);
315 
316 /*! \brief Set the model of the remote machine, for inclusion in the file.
317  \param s The T.4 context.
318  \param model The model string, or NULL. */
319 SPAN_DECLARE(void) t4_rx_set_model(t4_rx_state_t *s, const char *model);
320 
321 /*! Get the current image transfer statistics.
322  \brief Get the current transfer statistics.
323  \param s The T.4 context.
324  \param t A pointer to a statistics structure. */
325 SPAN_DECLARE(void) t4_rx_get_transfer_statistics(t4_rx_state_t *s, t4_stats_t *t);
326 
327 /*! Get the short text name of an encoding format.
328  \brief Get the short text name of an encoding format.
329  \param encoding The encoding type.
330  \return A pointer to the string. */
331 SPAN_DECLARE(const char *) t4_encoding_to_str(int encoding);
332 
333 /*! \brief Prepare for reception of a document.
334  \param s The T.4 context.
335  \param file The name of the file to be received.
336  \param output_encoding The output encoding.
337  \return A pointer to the context, or NULL if there was a problem. */
338 SPAN_DECLARE(t4_rx_state_t *) t4_rx_init(t4_rx_state_t *s, const char *file, int output_encoding);
339 
340 /*! \brief End reception of a document. Tidy up and close the file.
341  This should be used to end T.4 reception started with
342  t4_rx_init.
343  \param s The T.4 receive context.
344  \return 0 for success, otherwise -1. */
345 SPAN_DECLARE(int) t4_rx_release(t4_rx_state_t *s);
346 
347 /*! \brief End reception of a document. Tidy up, close the file and
348  free the context. This should be used to end T.4 reception
349  started with t4_rx_init.
350  \param s The T.4 receive context.
351  \return 0 for success, otherwise -1. */
352 SPAN_DECLARE(int) t4_rx_free(t4_rx_state_t *s);
353 
354 #if defined(__cplusplus)
355 }
356 #endif
357 
358 #endif
359 /*- End of file ------------------------------------------------------------*/
int x_resolution
The horizontal resolution of the page in pixels per metre.
Definition: t4_rx.h:227
void t4_rx_set_image_width(t4_rx_state_t *s, int width)
Set the expected width of the received image, in pixel columns.
Definition: t4_rx.c:1085
void t4_rx_set_x_resolution(t4_rx_state_t *s, int resolution)
Set the column-to-column (x) resolution to expect for a received image.
Definition: t4_rx.c:1097
Definition: t4_rx.h:212
t4_rx_state_t * t4_rx_init(t4_rx_state_t *s, const char *file, int output_encoding)
Prepare for reception of a document.
Definition: t4_rx.c:1177
const char * t4_encoding_to_str(int encoding)
Get the short text name of an encoding format.
Definition: t4_rx.c:1148
int t4_rx_set_row_write_handler(t4_rx_state_t *s, t4_row_write_handler_t handler, void *user_data)
Set the row write handler for a T.4 receive context.
Definition: t4_rx.c:1002
int pages_transferred
The number of pages transferred so far.
Definition: t4_rx.h:215
int line_image_size
The size of the image on the line, in bytes.
Definition: t4_rx.h:233
Definition: t4_rx.h:58
Definition: t4_rx.h:64
int t4_rx_put_byte(t4_rx_state_t *s, uint8_t byte)
Put a byte of the current document page.
Definition: t4_rx.c:981
void t4_rx_set_vendor(t4_rx_state_t *s, const char *vendor)
Set the vendor of the remote machine, for inclusion in the file.
Definition: t4_rx.c:1121
Definition: t4_rx.h:56
void t4_rx_get_transfer_statistics(t4_rx_state_t *s, t4_stats_t *t)
Get the current transfer statistics.
Definition: t4_rx.c:1133
Definition: t4_rx.h:66
int length
The number of vertical pixels in the most recent page.
Definition: t4_rx.h:221
t4_image_y_resolution_t
Definition: t4_rx.h:96
int t4_rx_end_page(t4_rx_state_t *s)
Complete the reception of a page.
Definition: t4_rx.c:581
Definition: t4_rx.h:62
int t4_rx_free(t4_rx_state_t *s)
End reception of a document. Tidy up, close the file and free the context. This should be used to end...
Definition: t4_rx.c:1246
Definition: t4_rx.h:52
Definition: t4_rx.h:54
Definition: t4_rx.h:70
Definition: t4_rx.h:68
void t4_rx_set_dcs(t4_rx_state_t *s, const char *dcs)
Set the DCS information of the fax, for inclusion in the file.
Definition: t4_rx.c:1103
int bad_rows
The number of bad pixel rows in the most recent page.
Definition: t4_rx.h:223
void t4_rx_set_model(t4_rx_state_t *s, const char *model)
Set the model of the remote machine, for inclusion in the file.
Definition: t4_rx.c:1127
int t4_rx_release(t4_rx_state_t *s)
End reception of a document. Tidy up and close the file. This should be used to end T...
Definition: t4_rx.c:1235
int t4_rx_start_page(t4_rx_state_t *s)
Prepare to receive the next page of the current document.
Definition: t4_rx.c:1010
int width
The number of horizontal pixels in the most recent page.
Definition: t4_rx.h:219
void t4_rx_set_sub_address(t4_rx_state_t *s, const char *sub_address)
Set the sub-address of the fax, for inclusion in the file.
Definition: t4_rx.c:1109
t4_image_width_t
Definition: t4_rx.h:124
t4_image_compression_t
Definition: t4_rx.h:49
int y_resolution
The vertical resolution of the page in pixels per metre.
Definition: t4_rx.h:229
t4_image_length_t
Definition: t4_rx.h:166
void t4_rx_set_y_resolution(t4_rx_state_t *s, int resolution)
Set the row-to-row (y) resolution to expect for a received image.
Definition: t4_rx.c:1091
void t4_rx_set_rx_encoding(t4_rx_state_t *s, int encoding)
Set the encoding for the received data.
Definition: t4_rx.c:1079
void t4_rx_set_far_ident(t4_rx_state_t *s, const char *ident)
Set the identity of the remote machine, for inclusion in the file.
Definition: t4_rx.c:1115
int t4_rx_put_bit(t4_rx_state_t *s, int bit)
Put a bit of the current document page.
Definition: t4_rx.c:975
int pages_in_file
The number of pages in the file (<0 if unknown).
Definition: t4_rx.h:217
t4_image_x_resolution_t
Definition: t4_rx.h:84
int t4_rx_put_chunk(t4_rx_state_t *s, const uint8_t buf[], int len)
Put a byte of the current document page.
Definition: t4_rx.c:987
int encoding
The type of compression used between the FAX machines.
Definition: t4_rx.h:231
Definition: t4_rx.h:60
Definition: private/t4_tx.h:35
int longest_bad_row_run
The largest number of bad pixel rows in a block in the most recent page.
Definition: t4_rx.h:225
t4_image_types_t
Definition: t4_rx.h:74
int(* t4_row_write_handler_t)(void *user_data, const uint8_t buf[], size_t len)
Definition: t4_rx.h:46